M.U.S.C.L.E. figures with lots of flash were likely from the end of a mold's life-span. (Note that every one of THE GODBEAST's custom Claws that I have purchased has had flash. I'm not sure what causes it. Maybe Marty could enlighten us?)
That is because I let the collectors get the claws for a better deal w/o me cleaning off the flashing. That is caused from my 2 part molds. The flashing is the little bit of plastic that leaks between the 2 halves at the seam. It saves me time not having to take an exacto to each of those claws' seams.
As far as fakes go, w/ any toy line, the buyer of such oddities has got to purchase such rarities from a trusted seller. They should also have clear photos and even purchase such items on the open forum for all to see. That way the buyer can see/hear other collector's opinions and knowledge.
I collected some super odd/rare vintage Star Wars, Smurf, BB/LB, Rocks Bugs & Things, etc... errors/variants. I can tell the difference fairly easily, also because I have seen a TON of customs, fakes, and just plain condition changes (dry rot, sun fading, nicotine, etc...)
I think if a seller posts their variant/error here w/ clear photos, this group is pretty savvy w/ items like these.
TGB